Utilization of N , P and organic C by heterotrophic bacteria . 11 . Comparison of experiments and a mathematical model

The consumption of ammonia as N-source, orthophosphate as P-source, and glucose as Csource was investigated in batch and chemostat cultures of Pseudornonas putida NCMB 1960. Consumption of nutrients and growth in cell numbers were compared to a general 'Droop' type mathematical model previously suggested. Important characteristics of the growth patterns in batch cultures such as depletion of more than one nutrient from the culture fluld, continued increase in cell numbers after depletion of one or more nutrients, and continued consumption of glucose after a stationary phase in cell numbers had been reached, could be explained by the model. The 3 nutrients were depleted from the cultures in various combinations dependent upon C : N : P-composition of the medium. In batch cultures, 4 different combinations of nutrient depletion were observed, while 3 additional combinations were observed in chemostat cultures. The observed patterns of nutnent deplehon could be explained w i t h the context of the proposed mathematical model. Three other bacterial strains of manne heterotrophc bacteria gave a similar qualitative pattern of substrate consumption in batch cultures, but different sets of numencal values were required for the parameters in order to fit the model to each strain. It is also demonstrated how the proposed model may be fitted to published experimental results describing the consumption of glucose and phosphate following the addition of phosphate to P-starved cultures of Vibno natriegens.